Abrupt climate shifts spurred Stone Age innovation in Africa

Stone Age innovation and climate change

Christopher Henshilwood / University of the Witwatersrand

These bifacial points recovered from Blombos Cave, South Africa, were manufactured during the Middle Stone Age about 75,000 years ago by anatomically modern humans. Scientists suggest that anatomically modern humans fashioned tools such as these about that time, when the area was warmer and...

These bifacial points recovered from Blombos Cave, South Africa, were manufactured during the Middle Stone Age about 75,000 years ago by anatomically modern humans. Scientists suggest that anatomically modern humans fashioned tools such as these about that time, when the area was warmer and... (Christopher Henshilwood / University of the Witwatersrand)

A European team suggests that one period of abrupt change, about 40,000-80,000 years ago in what now is South Africa, matches with a climate shift brought about by cyclical changes in the currents of the Atlantic Ocean. Their findings were published Tuesday in Nature Communications.

A period when the Atlantic no longer drew warm water toward upper latitudes, in a similar fashion to today’s gulf stream, created a colder Northern Hemisphere, a weaker Asian monsoon cycle and a band of temperate climate in South Africa, the team found.

Around this time, engraving and the manufacture of stone and bone tools and jewelry flourished in several areas of the south African cape, probably because of a climate shift that encouraged population expansion.

"The occurrence of several major Middle Stone Age industries fell tightly together with the onset of periods with increased rainfall," said Ian Hall, a paleoclimatologist at Cardiff University in Wales. "When the timing of these rapidly occurring wet pulses was compared with the archaeological data sets, we found remarkable coincidences.”

But as the local south African climate again shifted abruptly toward less rain during a warming in the Northern Hemisphere, innovation came to an apparent halt in one area about 59,000 years ago, and shifted east and north, the researchers found.

The team examined about 100,000 years of sediment cores from the mouth of the Great Kei River and matched periods of heavy sediment flow – indicating more rain – with temperature shifts gleaned from studies of Antarctic ice cores.

The climate changes and shifting locations of innovation could help explain the prevailing theory that anatomically modern man migrated from Africa, eventually replacing the Northern Hemisphere's Neanderthals.